This week’s image comes from the Air Force Space & Missile Museum, at the Cape Canaveral Air Station in Florida. It’s a picture of Agena A (right) and B (left) vehicles on outdoor static display:
The Agenas were multi-role space vehicles, born in the early days of the space race but in use for nearly thirty years by both NASA and the U. S. Air Force.
The first Agenas (later dubbed Agena-A) were spacecraft in and of themselves — built to carry out reconnaissance missions for the Air Force (photo reconnaissance, and for early warning of Soviet missile launches). As a result, the U.S.’ first film-return satellite (Discoverer / Corona / KH-1), infrared early-warning satellite (MIDAS, Missile Detection And Surveillance), and ELINT satellite (SAMOS, Satellite And Missile Observation System) were all built on an Agena-A backbone. First launched in 1959, it was only a matter of time until the Agena was upgraded and its missions extended.
So after 20 Agena A launches, the Agena-B variant was built with an improved engine and larger propellant tanks. Since the Agena B’s engine could be restarted in space, a much wider range of missions could be supported. So along with additional reconnaissance satellites, the Agena-B also came to be used as an upper stage — helping launch a number of spacecraft, including NASA’s Ranger missions to the Moon. At this point, Agenas were still being custom-built for each mission, so a later variant (Agena-D, a slightly modified Agena-B) became essentially a “standard” Agena. Agena-Ds would prove the most-used variant, flying missions until 1987 (including the Agena’s most famous use — as a rendezvous and docking target for Gemini missions in the 1960’s). In all, 365 Agenas were flown on missions for the USAF and NASA.
As an extra bonus, here’s some NASA video from the Gemini VIII mission — first to dock with an Agena, and so the first mission to ever dock two spacecraft in space. Oh, and if you’re not up on your space history, there’s some extra excitement for you after that as well (I’ll leave it to you to learn about that from the video…).